Add `recording` config block for quality / fps / resolution

[fayerman-source]

Expose recording quality controls in config.

• recording.mode: copy (native, default, lowest CPU) or reencode.
• When reencoding: fps, scale (e.g. 1280:-2), crf, videoBitrate, preset.
• Source resolution/fps is fixed by Ring; these can only reduce from native (to save disk/bandwidth), never increase.
• Verify -c copy actually works with the library's stream before defaulting to it; fall back to a visually-lossless reencode if not.